While options are good, I have had versa climbers at two of my past studios and they were the least used pieces in the gym. They are very compact, which is nice in a small space. But if no one uses it, it is just a waste of space. If space is the issue, go for it. I would advise you to show clients how to use it and encourage using it. Cost may also be a factor, but I am sure there are comprably priced alternatives like a stationary cycle. But treadmills are the most used pieces of cardio in any gym.
The first thing that pops to mind for me is to survey your current clients to see which one they would want to have available for them to use. They are the people who will use it so you want to purchase something they want. I used to work in a gym that had a versa climber and it was almost never used. I remember one woman who loved it, but very few other people used it. In my current facility after treadmills the most popular piece of cardio equipment is the Cybex Arc Trainer.